The growth of ornamental and food plants in controlled environments has been accomplished in the past in a variety of ways. The greenhouse is the classic form of partially controlled environment, the origin of which is lost in antiquity. The greenhouse serves to allow the control of humidity, temperature and air-born damage from wind and hail. On occasions, the greenhouse, having a transparent roof for the inlet of sunlight, has its growing day lengthened by the addition of artificial lighting.
Another form of controlled environment growing is sand culture in which sand or other particulate media is simply a replacement for soil. Still another form of controlled environment is water culture, called hydroponics, in which the plants are grown with their roots immersed in liquid solution supplying the needs of moisture plus nutrients. Another form of controlled environment is the sub-irrigation culture in which water type beds or benches are filled with an inert material which is irrigated from the bottom of the bed. These are all performed usually within enclosures with sunlight as the principal source of light.
It has been learned that plants may be raised totally under artificial light. Such systems employing a chamber with totally artificial lighting is described and disclosed in the Canadian Journal of Plants Science, Volume 52, pages 854-856, September, 1972. Such chambers, for example, are of wood with reflectorized plastic lining and with a number of fluorescent lamps supplemented by incandescent lamps at the top of the chamber directed towards a growing area below. Conditioned air and nutrients are just introduced into the chamber as required for plant growth.
The development of artificial lighting for certain ornamental plants, particularly those of a seasonal nature, has progressed to a point where lamps are designed to provide the desired wave length for the growth modification sought. The periods of illumination and darkness to correspond with the photo periodicity of particular plants has been accomplished by timers which energize the lamps for the desired light cycling.
Probably the most sophisticated of the controlled environmental plant systems is the phyotron or large controlled environmental enclosure as constructed in France and the United States and disclosed in The World of Plants, Volume 3, Encyclopedia of Life Science, copyright 1965, The Doubleday Company, Inc., Garden City, New York, pages 96-98. In each of the foregoing approaches, a number of factors affecting plant growth have been controlled principally for experimental purposes. If commercial production of food plants is sought on an economic basis, a major element of cost is still untouched by these prior art systems.
In particular, the steps of planting, plant managing and harvesting are still accomplished in the traditional manner of moving a complex machine or a skilled worker to each plant at the appropriate time to perform the required function. In some of the most modern environmentally controlled plant systems available today, the cultivating is still accomplished employing stoop labor methods by laborers as has been used since Biblical days.
Moreover, the characteristic of certain plants that their growth is enhanced by movement of their parts, as by mild wind, has been eliminated or ignored in controlled environments heretofore.